Wireless communications are becoming increasingly popular in today's fast paced world. Mobility and portability provided by the wireless technology are the merits that the conventional wired network does not have. In addition, the cost of setting up an infrastructure of wireless network is cheaper than that of a wired network, since a significant amount of layout cost can be saved. Moreover, the flexibility of wireless network is much better than that of a conventional wired network, since the wireless network can be setup easily at the location where is difficult to layout substantial cables for wired network. The cable required in a wired network for forming a physical contact between a transmitter and a receiver can be damaged due to aging, environmental influence or even insect/rat bits that generally requires the administrator of the wired network to spend a considerable amount of time for locating the problamatic cable and replacing it. On the other hand, the wireless network is free from the foregoing problem of the wired network. Any forms of electromagnetic radiation can be used as the transmission medium of a wireless network, such as infrared, radio, etc. However, infrared can be blocked by wall or by other solid object such that radio is the most common transmission medium used in wireless networks.
According to IEEE 802.11 specification, the operating bandwidth of 802.11a is between 5.18˜5.805 GHz, and the bandwidth for both the 802.11b and 802.11g specification is between 2.402˜2.483 GHz, which is the generally referred as Industrial, Scientific and Medical band (ISM). For example, currently in Taiwan, there are only 11 channels available for wireless network service provider, such as wireless access point, that is, in Taiwan it only provides three channels free from inter-interference in 802.11b specification, which are channel 1, 6 and 11. If there are more than three wireless network service providers, in a same area all using 802.11b specification, the fourth provider is going to suffer radio interference no matter which channel it choose to operate. For instance, when channel 6 is occupied by an access point and the same time that another access point also choose to use channel 6, the overall efficiency of the wireless network is not going to equal two times the efficiency of only one access point in the network, such as just 1.3 times the efficiency of one access point or even worse. The only method of preventing the above problem is by directing the new access point added in the wireless network to use a channel other than channel 6. However, the more person use the wireless network, the more access point is required. In this regard, radio interference between access points is inevitable and has to be prevented since there are only three channels that are fully separated from each other and are not going to interference with one another. Presently, there's no channel-searching method capable of automatically detecting an appropriate channel such that most users of wireless network do not know how to set up an operating channel. In view of the above description, the present invention provides a channel-searching method for wireless network service providers capable of detecting an optimum channel.